ligera_f | R Documentation |
This function performs the genetic association tests on every locus of a genotype matrix against a quantitative trait, given a precomputed kinship matrix.
The function returns a tibble containing association statistics and several intermediates.
This version calculates p-values using an F-test, which gives calibrated statistics under both quantitative and binary traits.
Compared to ligera()
, which uses the faster Wald test (calibrated for quantitative but not binary traits), this F-test version is quite a bit slower, and is optimized for m >> n
, so it is a work in progress.
ligera_f( X, trait, kinship, kinship_inv = NULL, covar = NULL, loci_on_cols = FALSE, mem_factor = 0.7, mem_lim = NA, m_chunk_max = 1000, V = 0, tol = 1e-15, maxIter = 1e+06 )
X |
The |
trait |
The length- |
kinship |
The |
kinship_inv |
The optional matrix inverse of the kinship matrix. Setting this parameter is not recommended, as internally a conjugate gradient method ( |
covar |
An optional |
loci_on_cols |
If |
mem_factor |
Proportion of available memory to use loading and processing genotypes.
Ignored if |
mem_lim |
Memory limit in GB, used to break up genotype data into chunks for very large datasets.
Note memory usage is somewhat underestimated and is not controlled strictly.
Default in Linux and Windows is |
m_chunk_max |
Sets the maximum number of loci to process at the time. Actual number of loci loaded may be lower if memory is limiting. |
V |
Algorithm version (0, 1, 2). Experimental features, not worth explaining. |
tol |
Tolerance value passed to |
maxIter |
Maximum number of iterations passed to |
Suppose there are n
individuals and m
loci.
A tibble containing the following association statistics
pval
: The p-value of the association test
beta
: The estimated effect size coefficient for the trait vector at this locus
f_stat
: The F statistic
df
: degrees of freedom: number of non-missing individuals minus number of parameters of full model
The popkin
and cPCG
packages.
# Construct toy data # genotype matrix X <- matrix( c(0, 1, 2, 1, 0, 1, 1, 0, 2), nrow = 3, byrow = TRUE ) trait <- 1 : 3 kinship <- diag( 3 ) / 2 # unstructured case tib <- ligera_f( X, trait, kinship ) tib
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